The invention relates to a method for increasing pressure in cylinders used for oil hydraulic, water hydraulic, emulsion hydraulic as well as plasma and other fluid hydraulic systems, in which two part or multi-part cylinders are moved apart or together in a controlled fashion by means of valves, and the introduced pressure transducer, which has passed a high pressure pump, whereby in the piston surface cavity beneath the respective piston a specified pressure, even after separation from one another, is generated and maintained through compression of the piston surface cavity. The invention moreover relates to a cylinder for performing the method, comprising a foundation with cylinder housing, the body being connected to a high pressure pump via a supply line, as well as a piston/piston rod displaceable therein and the piston surface cavity formed beneath the piston between the cylinder cover and piston, piston rod and cylinder housing, as well as a compressor that can be inserted in the piston surface cavity.
When actuating cylinders and similar devices, the movement is created by feeding a pressure-transmitting agent, involving oil, water, water in an oil emulsion, plasma or other fluids or also air. By hydraulics is meant the theory and technical application of flows in compressible fluids. This means that in hydraulic systems, the fluid, above all oil or also water in an oil emulsion, initially must be appropriately acted upon in a high pressure pump, i.e. it is prestressed, and is then supplied to the cylinder via hoses or similar lines. The extension and the retraction of the cylinders is controlled by means of valves, always occurring at one and the same pressure level, namely the pressure level that is dependent upon the output of the high pressure pump. Especially in underground mining, where water in an oil emulsion is used for safety reasons, at present 400 bar max. is used, simply because currently no pumps are available which are able to generate a higher pressure level. Due to various circumstances, however, it is not always guaranteed that the afore-mentioned pressure is available in the piston surface cavity, so so-called adjustment circuits are known in underground mining and tunnel construction which allow the volume in the piston surface cavity to be adjusted through re-connection to the high pressure pump such that the above-mentioned pressure level is approximately available. It is not possible, however, to generate a higher pressure level within the piston surface cavity and hence within the cylinder because, as said before, said pumps are not in a position to do so. Yet for various reasons this is frequently desirable, with the pumps in the case of the aforementioned current highest pressure level of 400 bar representing a limit, while in the case of a lower pressure level, the costs of an additional high pressure pump and corresponding hoses would essentially once again compensate for the advantage.
The invention is therefore based on the object of creating a method and a device which enable the operation of cylinders at a randomly increased internal pressure (operating pressure) in relation to the pump pressure.
The object is achieved from a method point of view in that the cylinder is first fed a pressure-transmitting medium (oil, water, emulsion, plasma, compressed air) at a specified pressure level, based on which the cylinder can be displaced, and that thereupon the pressure in the piston surface cavity beneath the piston is increased randomly by using the pressure-transmitting medium having the same pressure level to further compress the pressure-transmitting medium in the piston surface cavity.